I suggest you use iptables rules to block traffic to that port or use a firewall script like Shorewall or SuSEFirewall.
On my Computer I have installed a standard SuSE Linux 8.1 Pro with Grafik-Login. I want to detach the binding of my X-Server to an IP-Socket or restirct it to some IP-Adresses (localhost, ...)
In the config-file "/etc/X11/xdm/XServers" I have changed ":0 local /usr/X11R6/bin/X :0 vt07" to ":0 local /usr/X11R6/bin/X :0 vt07 -nolisten tcp". But nothing happens. After a reboot the X-Server ist still listening on port 6000.
Does any one knows how I can solve the problem?